Electrochemical conversion

Abstract

The present disclosure provides methods, compositions, devices, systems and uses that pertain to the electrochemical reduction of CO2 to CO. The application presents a class of electrodes, incorporating molecular catalysts in nanostructures, for robust and efficient electrochemical systems, specifically, selective and robust hybrid electrodes, by incorporating a rhenium (Re) catalyst into the structure of highly porous heterogeneous materials. These electrodes can be scaled up to desired manufacturing dimensions due to their robust nature and methods of preparation.

1 . A composition comprising a rhenium catalyst and a carbon support wherein:
 the rhenium catalyst has a formula of Re(4,4′-R-2,2′-bipyridine)(CO) 3 X;   R is an electron donating group or an electron withdrawing group;   X is a halogen, acetonitrile, CH 3 CN(OTf), or Py(OTf); and   wherein the rhenium catalyst is dispersed on a surface of the carbon support.   
     
     
         2 . The composition of  claim 1 , wherein the carbon support is multi-walled carbon nanotubes. 
     
     
         3 . The composition of  claim 1 , wherein X is a halogen. 
     
     
         4 . The composition of  claim 1 , wherein X is chloro. 
     
     
         5 . The composition of  claim 1 , wherein R is an electron donating group. 
     
     
         6 . The composition of  claim 1 , wherein the rhenium catalyst is Re(tBu-bpy)(CO) 3 Cl. 
     
     
         7 . The composition of  claim 1 , wherein R is an electron withdrawing group. 
     
     
         8 . The composition of  claim 1 , wherein the composition is characterized by a current density of at least about 4 mA/cm 2 . 
     
     
         9 . The composition of  claim 1 , wherein the composition is characterized by a current density of about 4 mA/cm 2 . 
     
     
         10 . The composition of  claim 1 , wherein the composition is characterized by a turnover number (TON) greater than about 5600 and a turnover frequency (TOF) greater than about 1.6 s −1 . 
     
     
         11 . A method for electrocatalytically reducing CO 2  to CO, comprising: contacting an electrode with CO 2 ;
 wherein the electrode is in an aqueous solution having a pH of at least 4, comprising an electrolyte;   wherein the electrode comprises the composition of  claim 1 ; and   wherein the method is performed at a temperature of at least about 5° C.   
     
     
         12 - 18 . (canceled) 
     
     
         19 . The method of  claim 11 , wherein the selectivity for CO over H 2  is at least about 99%. 
     
     
         20 . The method of  claim 11 , wherein the selectivity for CO over H 2  is from about 30% to about 100%. 
     
     
         21 . The method of  claim 11 , wherein the method is characterized by a Faradaic efficiency of at least about 99%. 
     
     
         22 . The method of  claim 11 , wherein the electrolyte comprises KHCO 3 . 
     
     
         23 . The method of  claim 11 , wherein the method is performed at a temperature of from about 5° C. to about 35° C. 
     
     
         24 . (canceled) 
     
     
         25 . The method of  claim 11 , wherein the pH of the aqueous solution is from about 6 to about 8. 
     
     
         26 - 30 . (canceled) 
     
     
         31 . A process for preparing an electrode, comprising:
 suspending a rhenium catalyst, a carbon support, and carbon nanofiber in ethanol to form a suspension;   sonicating the suspension;   drop-casting the suspension onto a glassy carbon plate to form a drop-casted glassy carbon plate;   drying the drop-casted glassy carbon plate at a temperature from about 100° C. to about 180° C. for about 0.5 to about 24 hours; and   wherein the rhenium catalyst is the rhenium catalyst according to  claim 1 .   
     
     
         32 - 39 . (canceled) 
     
     
         40 . The process of  claim 31 , wherein the suspension is drop-casted at a temperature from about 40° C. to about 80° C. 
     
     
         41 . (canceled) 
     
     
         42 . The process of  claim 31 , wherein the drop-casted glassy carbon plate is dried at a temperature of about 150° C. for about 1 hour. 
     
     
         43 . (canceled)